The present invention relates to elastic garments or wraps that exert a compressive force when worn. An aspect of the invention is a compression stocking useful in the prevention and/or treatment of medical conditions of the lower extremities and vascular system in the lower extremities.
Therapeutic garments and elastic bandages that exert a compressive force are often utilized in the prevention and therapy of lower extremity vascular system disorders, such as edema, emboli, and thrombophlebitis. For example, compressive stockings are utilized to improve vascular circulation and to reduce edema and the possibility of emboli in the legs. Compression therapy is often utilized for the prevention and treatment of conditions caused by chronic venous insufficiency, including stasis ulceration in the leg. Elastic bandages, for example, have traditionally been used for compressive therapy of vascular disorders, including ulcers, of the lower extremities.
Therapeutic or compressive stockings are constructed to apply compressive pressure to a wearer""s legs. Compressive pressure may be greatest at the foot and gradually decrease from the foot towards the upper, or proximal, part of the leg. Alternatively, compressive pressure may be greatest at the ankle and gradually decrease towards the upper part of the leg. The amount of compressive pressure applied depends on the particular use and needs of the wearer. In order to achieve the intended preventative and/or therapeutic effect and to avoid complications of compressive pressure intervention, compressive pressure must be applied accurately. For example, should a greater amount of compressive pressure be applied higher on the leg than lower on the leg, blood flow may be impaired with a possible tourniquet effect occurring.
Further details on therapeutic compressive stockings, their use and construction, may be found in U.S. Pat. Nos. 4,015,448, issued Apr. 5, 1977; U.S. Pat. No. 4,172,456, issued Oct. 30, 1979; U.S. Pat. No. 4,513,740, issued Apr. 30, 1985; U.S. Pat. No. 4,745,917, issued May 24, 1988; and U.S. Pat. No. 5,005,567, issued Apr. 9, 1991. The disclosure of each of these patents is hereby incorporated herein by reference.
When elastic bandages are used, the bandages are wrapped onto the leg with the greatest pressure at the foot or ankle, and compressive pressures are manually reduced as the bandages are wrapped up the leg. Applying correct pressures at particular locations, and properly graduating pressures, so as to avoid creating a tourniquet effect when wrapping elastic bandages is difficult. Elastic bandages also come in a variety of styles, with stretch characteristics varying widely from product to product, making proper application of correct compression difficult.
The compressive pressure applied by stockings at a particular anatomical location may be determined and measured by various techniques. As will be recognized in the art, there is no standardized system for testing and measuring compressive pressures. A commonly used system for measuring compressive pressures is a British system, which may be used with pressure testing equipment made by Instron and by Hatra. (See, British Standard Specification for Graduated Compression Hosiery, BS 6612: 1985.) The British system divides compressive pressures into three levels, each level being referred to as a class. In Class I, 14 to 19 mm Hg (millimeters of mercury) of compressive pressure is provided. In Class II, 18 to 25 mm Hg of compressive pressure is provided. In Class III, 24 to 35 mm Hg of compressive pressure is provided. A Class I stocking would therefore provide 14 to 19 mm Hg of compressive pressure at the point of greatest compressive pressure. A Class II stocking would provide 18 to 25 mm Hg of compressive pressure at the point of greatest compressive pressure, and a Class III stocking would provide 24 to 35 mm Hg compressive pressure at the point of greatest compressive pressure. Suggested preventative and therapeutic uses for each class of pressure are also defined by the British system. Another system for measuring compressive pressures is a German system, which may be used with testing equipment made by Holenstein. The German system categorizes compressive pressures between 20 and 30 mm Hg as Class I, between 30 and 40 mm Hg as Class II, and between 40 and 50 mm Hg as Class III. (See also, European Committee for Standardization, CEN-TC 205WG2 Medical Compression Hosiery.)
There are no recognized standards for testing elastic bandages to accurately determine compressive pressures. Pressures applied by elastic bandages have been described by the amount of stretch of the elastic material, such as 50%, 100%, and 200%. Controlling the amount of compressive pressure a bandage will exert when applied requires extensive technical knowledge of bandage stretch characteristics, as well as experience. Some elastic bandages have incorporated methods to assist a care-giver in proper application. For example, visual indicators may be used to signify the degree of stretch, and thus compressive force, provided by an elastic bandage. A continuous pattern of geometric shapes may be formed on an elastic bandage by using indicator yams or with print. Either the shape of the geometric design or the spacing between shapes in a pattern may change when tension is applied to the bandage, indicating a change in compressive force. Such designs in elastic bandages have been used to indicate compressive pressures as high as 40 to 50 mm Hg.
Compressive stockings, due to the compressive pressures they apply, are generally more difficult to place on the leg than conventional dress hosiery. To be most effective, the area or areas of the stockings having the highest compressive pressure, and thus the most difficult to apply, should be located at the feet or more distal portions of the leg, such as the ankle. Consequently, compressive stockings are often especially difficult for the elderly or persons with compromised mobility to apply to their legs. In addition, higher compressive pressures are indicated for the prevention and treatment of leg ulcerations. As a result, compressive stockings that use higher compressive pressures, such as for leg ulcerations, may be even more difficult to apply.
It has been generally found that most persons can place, or apply, Class I stockings with minimal or no assistance. However, many patients are unable to apply or remove stockings with Class II or Class III pressures without assistance by a care-giver or medical personnel. Such stockings may also be difficult for the care-giver to apply. As discussed above, compression therapy is often utilized for the prevention and treatment of ulcers, for which Class II or Class III compressive pressures may be beneficial. Often, patients suffering from leg ulcers have difficulty applying stockings with Class II or Class III compressive pressures due to age or disability, such as compromised mobility. Such patients may also have difficulty removing such stockings, particularly if they are applied by a care-giver. It may also be difficult for a care-giver to remove such stockings due to the compressive pressures involved.
For compressive therapy to be most effective, higher pressures may be required. The very high pressures that may be required for both prevention and therapy may preclude use of a stocking, as construction of a stocking having such higher compressive force may cause the stocking to be too tight to apply over the heel of a person""s foot. As an alternative, high pressure elastic bandages which can be applied directly to a leg, without placement over the foot as with compressive stockings, may be used. Pressures higher than those supplied by a stocking can be applied by an elastic bandage. Using a high pressure elastic bandage, a leg is generally wrapped by a care-giver, rather than by a patient, as applying desired pressures with proper pressure graduation up the leg requires training and experience. Because of the difficulty of properly applying elastic bandages, they may be left on a patient for longer periods than a compressive stocking.
Higher compressive pressures and a wider range of pressures can be obtained by utilizing multiple stockings in layers. The layering of compressive pressures will produce a cumulative pressure effect. Layering a stocking that provides 10 mm Hg pressure with a Class I stocking would produce a stocking with Class II pressure. Layering a stocking that provides 10 mm Hg pressure with a Class II stocking would produce a stocking with Class III pressure. Layering two Class I stockings may produce Class II compressive pressures. Similarly, applying a Class II stocking over a Class I stocking may produce Class III compressive pressures. Layering of stockings allows the use of higher compressive pressures indicated for certain medical conditions. Since compression stockings are constructed having specific compressive pressures, layering of stockings to achieve specific higher, cumulative, compressive pressures eliminates the uncertainty of pressures resulting from application of elastic bandages. In addition, using multiple layers of compression stockings, patients and care-givers can apply a wide variety of accurate pressures.
However, there are many problems associated with layering multiple stockings. One problem is that it is difficult to coordinate the compressive pressures applied by each stocking to achieve a desired increased pressure at particular anatomical locations on the lower extremities. Should the areas of compressive pressure not align correctly, it is possible that the area of highest pressure may be on a more proximal, and thus undesired, area of the leg, and a tourniquet effect may result. Further, any ridges or wrinkles in the stockings, introduced either during construction of the stockings or as the stockings are applied, may cause discomfort to the wearer and/or produce an undesired localized pressure point on the skin of the wearer. Because high pressures are often required, such ridges could also eventually cause or exacerbate skin break down and result in ulcerations and other compromise of vascular flow and/or tissue integrity. When elastic bandages are used, the bandages overlap when applied, or may overlap more as they are worn, and create a localized pressure point that may cause skin irritation, breakdown, and ulceration.
Accordingly, there remains a need for compression stockings that are able to accurately achieve Class II, Class III, or greater compressive pressures at particular anatomical locations with proper pressure gradations and a smooth surface against the skin, while being easier to apply, than compression stockings and elastic compression bandages currently available. There is also a need for higher pressure compression stockings that are easier to correctly apply and that can be made efficiently and economically.
These needs, as well as other needs, are met by the present invention.
The present invention provides compression garments and bandages that overcome the disadvantages of currently available compression garments and elastic compression bandages and provide advantages to the wearer and care-giver.
One aspect of the present invention is a multilayer compression stocking system for use on a person""s lower extremities. The compression stocking system comprises a plurality of layers including an underlayer and at least one overlayer. The underlayer may be worn next to the skin or over another stocking, bandage or garment and includes predetermined amounts of compressive pressure at discrete locations. The underlayer further includes alignment markings to assist a wearer in positioning the underlayer on their leg. The alignment markings may be located at the locations of compressive pressure or at different locations on the underlayer.
The overlayer or overlayers is/are applied over the underlayer. As discussed below with reference to other aspects and embodiments of the present invention, one or more of the overlayers may include alignment markings that may or may not correspond to the alignment markings on the underlayer. In an embodiment of the present invention, the overlayer is aligned simply by aligning the toe and heel portions of the underlayer and the overlayer. In alternative embodiments, as discussed below, alignment markings are utilized to align the overlayer and underlayer.
The overlayer may or may not include areas of compressive pressure depending on the application. The uppermost overlayer may be constructed and/or colored to have a pleasing cosmetic appearance.
Further details of possible embodiments of the underlayer and the overlayer are set forth below with reference to additional embodiments of the present invention.
Another aspect of the present invention is a multilayer compression stocking system comprising: a first layer, or underlayer, providing a predetermined amount of compressive pressure; at least one overlayer providing a predetermined amount of compressive pressure; and each layer including an alignment marking or markings so that the layers may be aligned, thereby aligning the areas of compressive pressure. Predetermined compressive pressures for each layer may be less than Class I pressure and may be Class I, Class II, and/or Class III pressures, or higher. More than one overlayer may be utilized to produce the compressive pressures desired. For example, an underlayer and additional overlayers may be layered to provide a total compressive pressure in a Class I range. As another example, an underlayer and two additional layers, each providing Class I compressive pressures, may be utilized to achieve Class III compressive pressures. The overlayer may be colored and/or constructed to provide an attractive appearance. For example, an overlayer may be provided in colors and/or patterns of conventional dress hosiery.
As will be recognized in the art, there is no standardized system for testing and measuring compressive pressures. The compressive pressure applied by stockings at a particular anatomical location may be determined and measured by various techniques. A commonly used system for measuring compressive pressures is a British system, which may be used with pressure testing equipment made by Instron and by Hatra. The British system divides compressive pressures into three levels, each level being referred to as a class. In the British system, Class I provides 14 to 19 mm Hg of compressive pressure, Class II provides 18 to 25 mm Hg of compressive pressure, and Class III provides 24 to 35 mm Hg of compressive pressure. Thus, at the point of greatest compressive pressure, a Class I stocking would provide 14 to 19 mm Hg of compressive pressure, a Class II stocking would provide 18 to 25 mm Hg of compressive pressure, and a Class III stocking would provide 24 to 35 mm Hg compressive pressure. Suggested preventative and therapeutic uses for each class of pressure are also defined by the British system. Another system for measuring compressive pressures is a German system, which may be used with testing equipment made by Holenstein. The German system categorizes compressive pressures between 20 and 30 mm Hg as Class I, between 30 and 40 mm Hg as Class II, and between 40 and 50 mm Hg as Class III.
A multilayer compression stocking system of the present invention may further comprise a final outer layer without medically therapeutic compressive pressures. The final outer layer may be colored and/or constructed to provide an attractive cosmetic appearance, for example, an appearance similar to non-compressive dress hosiery.
In use, an underlayer may be applied first to a wearer""s leg and then an overlayer applied up and over the underlayer. Alignment markings on each layer may then be aligned to create the desired areas and amounts of compressive pressure and to ensure that the pressures are properly graduated, for example, in decreasing amounts up the leg. A final outer layer, if utilized, may then be applied up and over the compressive underlayer and overlayer.
A multilayer compression stocking of the present invention may be produced utilizing a circular knitting machine. Suitable yams and knitting techniques include those set forth in the patents referred to above and incorporated herein by reference. It is generally preferable to construct the stocking without seams. Seamless construction provides the advantage of avoiding ridges or wrinkles, which may lead to deterioration of the skin. The multilayer compression stocking may be produced in different sizes, both in length and circumference, for use by a wide variety of people. Pressures graduations along the length of each layer would preferably be constructed the same so that the pressures are matched at the same location on each layer, ensuring the proper cumulative pressure effect and the proper pressure gradation when applied to a leg. The multilayer compression stocking may be any size, style, or length. For example, the multilayer compression stocking may be of knee length, or may extend above the knee in mid-thigh length, full-thigh length, or may be pantyhose. The underlayer could also be of a different length than the outer layer or layers. For example, the underlayer could be of knee length with the outer layer or layers thigh length.
A further aspect of the present invention is a multilayer compression bandage system. The bandage system comprises a plurality of layers including an underlayer and at least one overlayer. The underlayer may be worn next to the skin or over another bandage or garment and includes predetermined amounts of compressive pressure at discrete locations. The underlayer further includes alignment markings to assist a wearer in positioning the underlayer on their body. The alignment markings may be located at the locations of compressive pressure or at different locations on the underlayer.
The overlayer or overlayers is/are applied over the underlayer. As discussed below with reference to other aspects and embodiments of the present invention, one or more of the overlayers may include alignment markings that may or may not correspond to the alignment markings on the underlayer. In an embodiment of the present invention, the overlayer is aligned simply by aligning the top and bottom portions of the underlayer and the overlayer. In alternative embodiments, as discussed below, alignment markings are utilized to align the overlayer and underlayer.
The overlayer may or may not include areas of compressive pressure depending on the application. The uppermost overlayer may be constructed and/or colored to have a pleasing cosmetic appearance.
Further details of possible embodiments of the underlayer and the overlayer are set forth below with reference to additional embodiments of the present invention.
A further aspect of the present invention is a multilayer compressive bandage system comprising: a first layer, or underlayer, providing a predetermined amount of compressive pressure; at least one overlayer providing a predetermined amount of compressive pressure; and each layer including an alignment marking or markings so that the layers may be aligned, thereby aligning the areas of compressive pressure. Predetermined compressive pressures for each layer may be less than Class I pressure and may be Class I, Class II, and/or Class III pressures, or higher. More than one overlayer may be utilized to produce the compressive pressures desired. For example, an underlayer and two additional layers, each providing Class I compressive pressures, may be utilized to achieve Class III compressive pressures. The overlayer may be colored and/or constructed to provide an attractive appearance. For example, an overlayer may be provided in colors and/or patterns of conventional dress hosiery.
A multilayer compressive bandage system of the present invention may further comprise a final outer layer without medically therapeutic compressive pressures. The final outer layer may be colored and/or constructed to provide an attractive cosmetic appearance.
As will be understood by those of ordinary skill in the art, a multilayer compression system and method of the present invention may be utilized in multiple areas on a patient, including, but not limited to the leg; including upper and lower legs; foot; arm, including upper and lower arms; hand; torso; head and other locations where compression is desired. The amount of compressive force exerted by the multilayer compression bandage may be varied as described herein so as to provide the degree of compressive force desired at a particular location.
An advantage of the present invention is that a layering system allows a person to receive more compressive pressure than otherwise possible.
Another advantage of the present invention is that alignment markings or areas allow different layers to be correctly aligned to provide the desired compressive pressures at particular anatomical locations and proper pressure gradations along the length of the leg.
Another advantage of the present invention is that easier placement of compression stockings with higher total compressive pressures is allowed by the use of layers. As a result of such easier placement, compliance with use of higher pressure compression stockings as part of a medical regimen by elderly persons and those with compromised strength or mobility is enhanced.
Another advantage of the present invention is higher pressure compression stockings that are easier to correctly apply can be made efficiently and economically. An underlayer stocking is preferably constructed from nylon-covered spandex yarns alternating with relatively fine count nylon yarns to enhance ease of application by reducing friction and to reduce wrinkling upon application of the overlayer or overlayers.
An underlayer stocking is preferably constructed with mild or little compressive pressure in the toe area. Toe construction is preferably of a durable nylon yarn in the size range of fine to medium denier, or is reinforced through knitting techniques, to reduce the chance of cutting by toe nails. Construction with mild or little compressive pressure will generally decrease the risk of undesired pressure and reduce the chance of skin breakdown on the ends of the toes. The toe area is preferably constructed of high stretch modulus yarns so that the area will conform to the shape of the toes.
The instep of the underlayer stocking will generally be constructed to provide more compressive pressure than the toe area. Preferably the underlayer is constructed so that there is a smooth transition in material between the toe area and the instep area, without ridges, to minimize the chance,of producing an undesired localized pressure point on a wearer""s skin. A smooth transition in construction may be accomplished, for example, by programming a knitting machine to enable a gradual change from one compression level to another, thereby eliminating a sharply defined line of pressure differential in the stocking.
To further reduce the chance of skin breakdown and to reinforce the stocking fabric, yarns with high strength and low coefficient of friction properties, such as Teflon, can also be incorporated into the fabric. Areas of the stocking including the toe, the top of the instep, and the heel may be reinforced in such a manner.
The heel area and ankle area of the underlayer stocking are preferably visually marked. Suitable marking techniques include using a knitted-in colored yarn, of a different color than the base yarn; a knit change; or marking by printing or applying a color to the heel area. Marking of the heel and ankle areas will assist in the alignment of the underlayer by allowing the marked heel area of the underlayer to be properly positioned on a wearer""s foot.
Knitting between the toe area and the heel area of the underlayer will preferably reflect the anatomical shape of the foot in that area. Knitting between the ankle and calf will reflect the anatomical shape of the leg; for example, a typical hourglass shape may be utilized.
An underlayer stocking is preferably constructed so that it has compressive pressures in desired locations, including, the instep, heel, ankle, calf, knee, and/or thigh. Compressive pressures will generally gradually reduce from the distal portion of the stocking towards the proximal, or upper, portion of the stocking.
In order to facilitate correct placement of the underlayer stocking on the leg of a wearer, the stocking would be preferably knitted with yarns, and in a manner, so as to provide stretch in both the horizontal and vertical directions (i.e., at least two-way stretch). This feature will permit the stocking fabric to adjust for minor variations in anatomy in the ankle and/or knee areas.
As described above, according to the present invention, a multilayer compression stocking includes alignment markings to permit each stocking layer to be correctly placed on the wearer, and with respect to other stocking layers, so as to achieve the desired compressive pressure in the desired areas of the stocking and thus at desired locations on the leg of the wearer. The alignment markings may comprise a different color yarn, a knit change, printing, and/or other markings to differentiate discrete locations on a stocking. For example, during construction of a compressive pressure of the stocking, the knitting machine could be programmed to insert a yarn or provide a knit change at a desired location to produce an alignment marking. Preferably, the alignment marking will not introduce a rib or other wrinkle in the stocking layer that could cause a localized pressure point on a wearer""s skin.
In general, it may be preferable for at least one set of alignment markings to correspond, or be located near, areas of greatest compressive pressure in a stocking. Thus, for example, alignment markings may be located near the heel and/or ankle region of each stocking layer. To facilitate and increase alignment, additional sets of alignment markings could be located in other areas, for example, the calf, instep, or other portions of the stocking. As an example, if pressure graduations are the same in each layer as preferred, alignment of the tops of the stocking layers, such as the tops of knee-length stocking layers, could also provide proper placement of stockings.
Additional stocking layers may be similar to the underlayer, with appropriate alignment markings and pressure characteristics and produced in similar manners. A final outer stocking layer may be colored and/or knitted in a fashion to provide an attractive cosmetic appearance. For example, a final outer stocking layer may be provided in colors and/or patterns of conventional dress hosiery.
An overlayer stocking is preferably constructed so that areas of compressive pressure have pressure characteristics and gradation that match the pressure characteristics and gradation of an underlayer. As an example, when compressive pressure is greatest at the ankle area for the underlayer, the greatest compressive pressure for the overlayer is preferably also at the ankle area, and both underlayer and overlayer are preferably aligned with each other and at the same place on the wearer""s ankle. As discussed above, should the pressures along the length of the leg be misaligned, accurate placement of specifically desired higher pressures may not be achieved, resulting in a less effective stocking system, and a tourniquet effect could occur.
As will be realized from the foregoing discussion, the stocking layers in the system of the present invention may comprise separate articles. Alternatively, each of the stocking layers may be joined to create a multilayer compression stocking comprising a single article. For example, the multiple layers may be joined in the toe region.
A multilayer compression stocking of the present invention may be applied by first positioning the underlayer on the leg of a wearer. Each overlayer is then positioned over the underlayer, or the layer immediately underneath, by matching the toes, heels, alignment markings, and tops of the layers. Such successive placement of stocking layers by aligning like areas and alignment markings ensures proper positioning of compressive pressures in desired locations.
In the present invention, an underlayer may comprise a stocking with visually distinctive alignment markings in the toe, heel, and top areas. A distinctive visual appearance may be obtained, for example, through coloring, use of colored yarn, and/or a knitting change. An underlayer may additionally comprise an alignment marking, for example, at the most narrow point of the ankle. Use of the ankle alignment marking, and visually distinctive heel, toe, and top areas allow the underlayer to be properly positioned on a person""s lower extremity.
An overlayer stocking may include visually apparent markings similar to those of an underlayer. Alternatively, an overlayer may include a visually distinctive heel region only. Alignment of the heel region and top of an overlayer with the heel region and top of an underlayer may provide sufficient alignment of the layers for a variety of applications.
Similar techniques may be utilized in the production and use of a multilayer compression bandage of the present invention. In certain embodiments, a non-circular knitting machine may be employed to produce multilayer compression bandages suitable for wrapping.
Those of ordinary skill in the art will appreciate the advantages and features of the present invention as described above and as is apparent from the detailed description below. As will be realized by those of skill in the art, many different embodiments of a multilayer compression stocking system according to the present invention are possible. Preferred embodiments of a multilayer compression stocking system will include one or more of the following features.